RETAINER RING FOR CHEMICAL MECHANICAL POLISHING APPARATUS AND CHEMICAL MECHANICAL POLISHING APPARATUS INCLUDING THE SAME

CROSS-REFERENCE TO RELATED APPLICATION

[0001]This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0166103 filed at the Korean Intellectual Property Office on Nov. 24, 2023, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

[0002]The present disclosure relates to a chemical mechanical polishing (CMP) apparatus, and more particularly, to a retainer ring for a chemical mechanical polishing (CMP) apparatus and a chemical mechanical polishing (CMP) apparatus including the same.

(b) Description of the Related Art

[0003]A chemical mechanical polishing (CMP) apparatus is used in a polishing process for planarizing a surface of a wafer that is a semiconductor substrate. Specifically, the CMP apparatus is an apparatus that planarizes the semiconductor substrate by pressing a polishing pad and the substrate toward each other and simultaneously rotating them relative to each other while supplying an abrasive including a slurry that is a mixture of insoluble material (power/particles) and a polishing liquid between the polishing pad and the substrate in a state in which the polishing pad and the substrate are pressed against each other.

[0004]The CMP apparatus may include a head portion that supports the substrate to polish the substrate. The head portion generally supports the substrate by a membrane, but if the substrate is supported only by the membrane, there is a problem in which the substrate is separated from the head portion. Thus, a retainer ring member is additionally disposed at the head portion to support the substrate.

[0005]The retainer ring member includes an inner ring and an outer ring, and includes an inclined surface between the inner ring and the outer ring to provide a path through which a chemical solution and a cleaning solution flow. However, if the flow path is designed only with the above inclined surface, there is a problem because it is difficult to change a slope or a size of the flow path in the CMP apparatus. In addition, if the slope of the inclined surface is changed, there is a problem because a change in an area of an upper plate region is large due to limitation of change of a bottom groove region so that it is difficult to change a design without changing a fastening structure.

SUMMARY OF THE INVENTION

[0006]Aspects of the present disclosure provide a retainer ring for a chemical mechanical polishing apparatus that facilitates a flow of a fluid in a flow space disposed between an inner ring and an outer ring and prevents a phenomenon in which the fluid overflows due to a back flow or the fluid pools or stagnates.

[0007]Another aspect of the present disclosure provides a chemical mechanical polishing apparatus including the retainer ring having the aforementioned advantage.

[0008]A retainer ring of a head portion in a chemical mechanical polishing apparatus according to an embodiment of the present disclosure includes: an inner ring configured to surround a circumference edge of a wafer; an outer ring surrounding the inner ring; and a fluid flow path formed between the inner ring and the outer ring, the fluid flow path defined by an outward-facing surface of the inner ring and an inward facing surface of the outer ring. The inward-facing surface of the outer ring includes at least one lower curved portion

[0009]A retainer ring of a head portion in a chemical mechanical polishing apparatus according to another embodiment of the present disclosure includes: an inner ring configured to surround a circumference edge of a wafer; an outer ring surrounding the inner ring; and a fluid flow path formed between the inner ring and the outer ring, the fluid flow path defined by a surface of the inner ring and a surface of the outer ring. The surface of the outer ring defining the fluid flow path includes at least one lower curved portion and at least one lower straight-line portion.

[0010]A chemical mechanical polishing apparatus according to an embodiment of the present disclosure includes: a polishing platen that is rotatable; a polishing pad that is disposed on the polishing platen; a head portion that is disposed above the polishing pad and configured to install a wafer; a slurry supplying portion configured to supply a slurry to the polishing pad; and a retainer ring in the head portion, the retainer ring configured to surround the wafer, the retainer ring including an inner ring configured to hold a circumference edge of the wafer, an outer ring surrounding the inner ring, and a fluid flow path disposed between the inner ring and the outer ring, the fluid flow path defined by an outward-facing surface of the inner ring and an inward-facing surface of the outer ring, wherein the inward-facing surface of the outer ring includes at least one lower curved portion.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011]FIG. 1 is a perspective view of a chemical mechanical polishing apparatus according to an embodiment of the present disclosure.

[0012]FIG. 2 is a plan view of the chemical mechanical polishing apparatus according to an embodiment of the present disclosure.

[0013]FIG. 3 is a cross-sectional view of the chemical mechanical polishing apparatus of FIG. 2 along a line A-A′ shown in FIG. 2.

[0014]FIG. 4 is a perspective view of a retainer ring according to an embodiment of the present disclosure.

[0015]FIG. 5 is a cross-sectional view of the retainer ring of FIG. 4 along a line B-B′ according to an embodiment of the present disclosure.

[0016]FIGS. 6 to 9 are enlarged views of a region P1 of FIG. 5 according to some embodiments of the present disclosure.

[0017]FIG. 10 and FIG. 11 are views for describing a length of a curved portion (or a bent portion) of the retainer ring according to another embodiment of the present disclosure.

[0018]FIG. 12 is a cross-sectional view of the retainer ring of FIG. 4 along the line B-B′ according to another embodiment.

[0019]FIGS. 13 to 17 are enlarged views of a region P2 of FIG. 12 according to some embodiments of the present disclosure.

[0020]FIG. 18 is a cross-sectional view of the retainer ring of FIG. 4 along the line B-B′ according to another embodiment.

[0021]FIGS. 19 to 23 are enlarged views of a region P3 of FIG. 18 according to some embodiments of the present disclosure.

[0022]FIG. 24 is a view for describing a length of the curved portion of the retainer ring according to another embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023]Hereinafter, embodiments of the present disclosure will be described more fully with reference to the accompanying drawings for a person of ordinary skill to easily implement the present disclosure. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit and/or scope of the present disclosure.

[0024]Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification.

[0025]In addition, because size and thickness of each component shown in the drawings are arbitrarily shown for convenience of description, the present disclosure is not necessarily limited to those illustrated in the drawings. In the drawings, the thicknesses of layers, films, panels, regions, areas, etc., are exaggerated for clarity. In the drawings, for ease of description, the thicknesses of some layers and areas are exaggerated.

[0026]It will be understood that when an element such as a layer, film, region, area, or substrate is referred to as being “on” or “above” another element, it may be directly on the other element or intervening elements may also be present. In contrast, when an element is referred to as being “directly on” another element, there are no intervening elements present. Further, in the specification, the word “on” or “above” means disposed on or below the object portion, and does not necessarily mean disposed on the upper side of the object portion based on a gravitational direction.

[0027]In addition, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements.

[0028]Further, throughout the specification, the phrase “in a plan view” or “on a plane” means viewing a target portion from the top, and the phrase “in a cross-sectional view” or “on a cross-section” means viewing a cross-section formed by vertically cutting a target portion from the side.

[0029]Hereinafter, embodiments of the present disclosure will be described in detail so that a person of ordinary skill in the technical field to which the present disclosure belongs may easily implement the present disclosure. However, the present disclosure may be implemented in many different forms, and is not limited to the embodiment described herein.

[0030]FIG. 1 is a perspective view of a chemical mechanical polishing apparatus 100 according to an embodiment of the present disclosure.

[0031]FIG. 2 is a plan view of the chemical mechanical polishing apparatus 100 according to an embodiment of the present disclosure.

[0032]FIG. 3 is a cross-sectional view of the chemical mechanical polishing apparatus 100 of FIG. 2 along a line A-A′.

[0033]Referring to FIGS. 1 to 3, the chemical mechanical polishing apparatus 100 is a device for polishing a wafer WF, and includes a polishing platen 110, a polishing pad 120, a head portion 130, a conditioner 140, and a slurry supplying portion 150. In the chemical mechanical polishing apparatus 100, mechanical polishing is performed when the wafer WF installed at a bottom surface of the head portion 130 contacts the polishing pad 120, and chemical polishing is performed through a chemical reaction by a slurry supplied from the slurry supplying portion 150.

[0034]The polishing platen 110 may be a member that applies a rotation energy to the polishing pad 120 so that the polishing pad 120 rotates in a certain direction. For example, the polishing pad 120 may be disposed on the polishing platen 110, and may rotate by driving the polishing platen 110. For example, the polishing pad 120 may rotate when the polishing platen 110 rotates by a driving force applied to the polishing platen 110.

[0035]The polishing pad 120 may uniformly planarize a surface of the wafer WF, and may be a member that performs the mechanical polishing. The polishing pad 120 may be disposed on the polishing platen 110 to rotate by driving the polishing platen 110. The polishing pad 120 may be provided as a circular plate, but the present disclosure is not limited thereto.

[0036]The polishing pad 120 may include a polishing surface with predetermined roughness. While a chemical mechanical polishing process is performed, the polishing surface of the polishing pad 120 may be in contact with the wafer WF to mechanically polish the wafer WF. It will be understood that when an element is referred to as being “connected” or “coupled” to or “on” another element, it can be directly connected or coupled to or on the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, or as “contacting” or “in contact with” another element, there are no intervening elements present at the point of contact.

[0037]The polishing pad 120 may include or be formed of a porous material having a plurality of micro-spaces, e.g., micro-pore spaces. For example, the micro-spaces of the polishing pad 120 may accommodate the slurry provided while the chemical mechanical polishing process is performed. As a non-limiting example, the polishing pad 120 may include or may be a polyurethane pad.

[0038]The head portion 130 may be a rotatable member at which a substrate (for example, the wafer WF) is installed. For example, the head portion 130 may rotate in a certain direction. The head portion 130 may be pressed in a direction approaching the polishing pad 120 so that the wafer WF is polished. As a non-limiting example, the wafer WF may be a semiconductor wafer made of silicon as a base material and having a circular shape/appearance. In some embodiments, the wafer WF may include a material such as gallium arsenide, sapphire, gallium nitride, a ceramic, a resin, or silicon carbide in addition to silicon. In come embodiments, no devices are formed on the wafer WF.

[0039]In an embodiment, the head portion 130 may include a membrane 130M which is in contact with the wafer WF when the wafer WF is loaded on the head portion 130. One surface of the membrane 130M may be exposed downwards when no wafer is loaded on the head portion 130 so that the membrane 130M is disposed on the wafer WF to load the wafer WF on the membrane 130M. The membrane 130M may be attached to the wafer WF, and may serve to control an external force depending on a region of the wafer WF. For example, the membrane 130M may be formed of a flexible material, and may be a member that assists to apply an independently controllable pressure to relevant regions on the wafer WF by a plurality of independently controllable pressing chambers.

[0040]In an embodiment, the head portion 130 may include a support plate 130S disposed on the membrane 130M to support the wafer WF and the membrane 130M. For example, the support plate 130S may be disposed on the membrane 130M to fix and support the wafer WF disposed on a lower surface of the membrane 130M and the membrane 130M.

[0041]In an embodiment, the head portion 130 may include a retainer ring 130R for fixing/holding the wafer WF. For example, the retainer ring 130R may extend from an end portion of the support plate 130S toward the wafer WF to prevent the wafer WF from being separated. For example, the retainer ring 130R may be implemented in a form of a ring surrounding the wafer WF when the wafer WF is attached onto the membrane 130M of the head portion 130, and may be disposed outside the wafer WF to prevent a detachment problem of the wafer WF that may occur during the polishing process. For example, the retainer ring 130R may surround all around the perimeter of the wafer WF while the polishing process is performed on the wafer WF. For example, the retainer ring 130R may hold the wafer WF to be maintained in a certain position with respect to the head portion 130 while the polishing process is performed.

[0042]In an embodiment, the retainer ring 130R may include an inner ring 131 for fixing the wafer WF, an outer ring 132 for fixing the inner ring 131, and a fluid flow path 133 disposed between the inner ring 131 and the outer ring 132 for a chemical solution or a cleaning solution to flow/move along the fluid flow path 133. The retainer ring 130R may have a split structure between the inner ring 131 and the outer ring 132, so that it may efficiently prevent the wafer WF from being detached. The retainer ring 130R may include the fluid flow path 133, so that the chemical solution flows between the inner ring 131 and the outer ring 132 and along a bottom surface where the polishing pad 120 is disposed, which may prevent a phenomenon in which the solution flows backward or stagnates/accumulates through the fluid flow path 133.

[0043]The fluid flow path 133 may be disposed between the inner ring 131 and the outer ring 132, and may be a space formed by the inner ring 131 and the outer ring 132. For example, the fluid flow path 133 may include at least one sub-fluid flow path defined by an inner surface formed by a surface 131S (e.g., an outer circumferential surface, or outward-facing surface) of the inner ring 131 and an inner surface formed by the surface 132S (e.g., an inner circumferential surface or inward-facing surface) of the outer ring 132. For example, the surface 131S of the inner ring 131 and the surface 132S of the outer ring 132 may be surfaces facing each other. In an embodiment, an upper portion of the inner ring 131 may be disposed higher than an upper portion of the outer ring 132.

[0044]In an embodiment, the outer circumferential surface 131S of the inner ring 131 within the fluid flow path 133 may include at least one upper curved portion 131SR. For example, the at least one upper curved portion 131SR may have a curved shape. For example, the upper curved portion 131SR may have a concave shape or a convex shape. For example, the surface 131S of the inner ring 131 may have multiple concave/convex surfaces in certain embodiments. Each of concave shapes formed in the fluid flow path 133 may be a recess formed on a surface of the fluid flow path 133 and may have a smooth and even surface along a circumferential direction of the retainer ring 130R and have a recessed shape/pattern in a direction perpendicular to the circumferential direction of the retainer ring 130R. Each of convex shapes formed in the fluid flow path 133 may be a protruding portion formed on a surface of the fluid flow path 133 and may have a smooth and even surface along a circumferential direction of the retainer ring 130R and have a protruding shape/pattern in a direction perpendicular to the circumferential direction of the retainer ring 130R.

[0045]The fluid flow path 133 may include the at least one upper curved portion 131SR, so that the chemical solution or the cleaning solution easily flows along a bottom surface where the polishing pad 120 is disposed, which may prevent a phenomenon in which the chemical solution or the cleaning solution flows backward and/or stagnates/accumulates. For example, when the chemical solution or the cleaning solution does not flow smoothly, it may be solidified in the flow path of the solution. The solidified material may fall on the polishing pad 120 and may cause a problem by acting as a particle which may damage the wafer WF.

[0046]In an embodiment, the head portion 130 may include a driving portion (not shown) that rotates the head portion 130. The driving portion (not shown) may be a member that controls the head portion 130 to be rotatable/rotated. In an embodiment, the head portion 130 may be rotatable/rotated by a first control portion (or a first controller) (not shown). For example, the first control portion may control the head portion 130 to be rotatable/rotated (e.g., with respect to a central axis of the head portion 130), so that the wafer WF installed at the head portion 130 is rotatable/rotated.

[0047]The conditioner 140 may be a member that conditions a surface of the polishing pad 120. For example, the conditioner 140 may maintain a surface roughness of the polishing pad 120 in an optimal state by polishing the surface of the polishing pad 120.

[0048]The conditioner 140 may recover or maintain the surface roughness of the polishing pad 120 by polishing the polishing pad 120 while the wafer WF is polished with the head portion 130 or in a state when the head portion 130 does not polish a wafer WF. In an embodiment, the conditioner 140 may include particles (for example, artificial diamond particles) fixed on a circular disk made of a metal using a nickel (Ni) adhesive layer. For example, the conditioner 140 may be formed of a metal disk, diamond particles attached on the metal disk, and nickel adhesive interposed between the metal disk and the diamond particles.

[0049]In an embodiment, the conditioner 140 may rotate in a direction. For example, the conditioner 140 may rotate at a constant speed while conditioning the polishing pad 120. For example, the conditioner 140 may rotate in the same direction as the polishing platen 110 and the head portion 130, and may control the roughness of the polishing pad 120.

[0050]The slurry supplying portion 150 may be a member that supplies a slurry to the polishing pad 120. The slurry supplying portion 150 may be disposed above or on the polishing pad 120, and may supply the slurry to the polishing pad 120. Thus, the slurry may be transferred to the wafer WF through the micro-space formed at the polishing pad 120 so that not only mechanical polishing of the wafer WF according to rotation of the head portion 130 but also chemical polishing by the slurry may be simultaneously performed.

[0051]FIG. 4 is a perspective view of the retainer ring 130R according to an embodiment of the present disclosure.

[0052]In an embodiment, the retainer ring 130R may include the inner ring 131 having an annular shape and the outer ring 132 having an annular shape, and may include the fluid flow path 133 that facilitates movement of a fluid between the inner ring 131 and the outer ring 132. The inner ring 131 and the outer ring 132 may have a cylindrical shape, and the fluid flow path 133 formed between the inner ring 131 and the outer ring 132 may also have a cylindrical shape. For example, each of the inner ring 131 and the outer ring 132 may have a circular bottom (e.g., having an annular shape), a circular top (e.g., having an annular shape) and a side surface connecting the circular bottom and the circular top.

[0053]In an embodiment, the inner ring 131 may be a member for fixing/holding the wafer WF in a certain position (e.g., with respect to the head portion 130), and a diameter of the inner ring 131 may be greater than a diameter of the wafer WF. For example, the diameter of the inner ring 131 (e.g., measured at an inner surface, facing the wafer WF, of the inner ring 131) may be 1 to 3 mm larger than the diameter of the wafer WF. In an embodiment, the outer ring 132 may be a member surrounding the inner ring 131, and may have a diameter larger than the diameter of the inner ring 131.

[0054]In an embodiment, a lower portion of the inner ring 131 may be a portion in contact with the polishing pad 120. For example, the lower portion of the inner ring 131 may be in contact with the polishing pad 120 while a polishing process is performed, and simultaneously, may rotate together with the head portion 130 as the head portion 130 rotates. At least a portion of the lower portion of the inner ring 131 may be formed of a chemically inert material in a CMP process. For example, at least the portion of the lower portion of the inner ring 131 may be a plastic material such as polyphenylene sulfide (PPS). This is a non-limiting example, and the lower portion of the inner ring 131 may be made of various materials having durability and wear resistance.

[0055]In an embodiment, the retainer ring 130R may include a lower outer ring 132B. The lower outer ring 132B may be disposed below the outer ring 132, may be disposed on a side surface of the inner ring 131 to fix/support the inner ring 131, and may reduce wear of the outer ring 132 and may be beneficial to prevent excessive wear of the outer ring 132 to improve durability of the outer ring 132. For example, the lower outer ring 132B may be a region in contact with the polishing pad 120 when the wafer WF is polished, and may be formed of a material harder than that of the outer ring 132. For example, the lower outer ring 132B may be formed of a harder material than those of the inner ring 131 and the outer ring 132.

[0056]In an embodiment, a recess structure through which the chemical solution or the cleaning solution may flow may be included between the lower outer ring 132B and the inner ring 131. For example, the recess structure may refer to a fine gap formed between the lower outer ring 132B and the inner ring 131. The chemical solution or the cleaning solution introduced into the fluid flow path 133 may be discharged downward through the fine gap.

[0057]In an embodiment, at least one fastening portion for coupling the membrane 130M and the support plate 130S of the head portion 130 may be included on upper surfaces of the inner ring 131 and the outer ring 132. This is a non-limiting example, and various methods may be used for coupling the inner ring 131 and the outer ring 132 together and for coupling the inner ring 131 and the outer ring 132 to the head portion 130.

[0058]FIG. 5 is a cross-sectional view of the retainer ring 130R of FIG. 4 along a line B-B′ according to an embodiment of the present disclosure.

[0059]The retainer ring 130R according to an embodiment of the present disclosure includes at least one fluid flow path 133 formed by the surface 131S of the inner ring 131 and the surface 132S of the outer ring 132. The chemical solution or the cleaning solution may move through the fluid flow path 133, and may remove an impurity (e.g., solid contents) accumulated around/in the fluid flow path 133.

[0060]In an embodiment, the surface 131S of the inner ring 131 may include at least one upper curved portion 131SR. The surface 131S of the inner ring 131 may include the curved portion that is not a straight-line member/portion in the surface 131S of the inner ring 131 and has a shape (for example, a convex shape) curved (or bent) in a diagonal direction between X and Z directions, so that movement of the fluid may be performed more smoothly when the chemical solution or the cleaning solution is supplied to the fluid flow path 133

[0061]FIGS. 6 to 9 are enlarged views of a region P1 of FIG. 5.

[0062]Referring to FIG. 6, in an embodiment, the surface 132S of the outer ring may include at least one lower curved portion 132SR. The lower curved portion 132SR may be a member/portion having a shape (for example, a convex shape) curved (or bent) in a diagonal direction between the X and Z directions. The surface 131S of the inner ring and the surface 132S of the outer ring constituting the fluid flow path 133 may include an upper curved portion 131SR and the lower curved portion 132SR, respectively, so that flow of the fluid may be further facilitated.

[0063]In an embodiment, the surface 131S of the inner ring may include a dummy surface portion 131SD. The dummy surface portion 131SD may be a member/portion formed/extending in a Z-axis direction (or the Z direction) at the surface 131S of the inner ring. The dummy surface portion 131SD may be a member/portion that assists the chemical solution or the cleaning solution introduced into the fluid flow path 133 to move downward through a fine gap between the lower outer ring 132B and the dummy surface portion 131SD.

[0064]In an embodiment, the lower curved portion 132SR may have a convex shape of a predetermined radius. For example, in the lower curved portion 132SR, an angle θ formed between a tangent line L1 at a point approaching an end of a curved surface of the surface 132S of the outer ring in a cross-sectional view as shown in FIG. 6 and a horizontal line L2 formed by (e.g., overlapping) a bottom surface of the outer ring 132 (for example, a bottom surface of the lower outer ring 132B) in the cross-sectional view, may be 90° or less. The lower curved portion 132SR may satisfy the above-described angle to prevent a phenomenon in which the chemical solution flowing at a lower portion of (e.g., below) the retainer ring 130R overflows or stagnates/accumulates.

[0065]In an embodiment, a minimum interval b1 between the lower curved portion 132SR and the upper curved portion 131SR may be 0.11 to 0.5 times a thickness a1 of the outer ring 132. For example, the minimum interval b1 may be obtained/measured in an area outside an area that includes a maximum interval between the surfaces of the upper curved portion 131SR of the inner ring 131 and the lower curved portion 132SR of the outer ring 132 forming the fluid flow path 133. For example, a value obtained by dividing the minimum interval b1 between the lower curved portion 132SR and the upper curved portion 131SR by a value of the thickness a1 of the outer ring 132 may satisfy 0.11 to 0.5, 0.11 to 0.30, 0.12 to 0.20, or 0.13 to 0.19. Because the value satisfies the above-described range, the chemical solution or the cleaning solution may be easily introduced into the fluid flow path 133, and the introduced solution may be discharged to a lower portion of the retainer ring 130R so that a phenomenon in which the solution overflows or stagnates/accumulates is prevented.

[0066]Referring to FIG. 7, in an embodiment, the surface 132S of the outer ring 132 may include a lower curved portion 132SR′ that is not a straight-line member/portion and has a shape (for example, a concave shape) curved (or bent) in a diagonal direction between a direction opposite to the X direction and a direction opposite to the Z direction. For example, tangent lines of the lower curved portion 132SR′ at a center point and/or throughout the curved portion 132SR′ may have negative values (e.g., negative slopes) in an X-Z coordinate shown in a cross-sectional view, e.g., in FIG. 7. Because the surface 132S of the outer ring includes the lower curved portion 132SR′ of the concave shape, it is possible to induce a larger amount of solution into the fluid flow path 133 and to smoothly move the fluid. In an embodiment, the surface 132S of the outer ring and the surface 131S of the inner ring 131 may have the same curved shape, e.g., be congruent with each other in a cross-sectional view. In another embodiment, the surface 132S of the outer ring and the surface 131S of the inner ring 131 may be disposed/formed in different shapes. The surface 132S of the outer ring and the surface 131S of the inner ring 131 may be implemented in a symmetrical or asymmetric shape depending on a design change.

[0067]Referring to FIG. 8 and FIG. 9, in an embodiment, the surface 131S of the inner ring may include an upper straight-line portion 131SL. The fluid flow path 133 may include the lower curved portion 132SR, and the surface 131S of the inner ring may additionally include various shapes in various embodiments.

[0068]FIG. 10 and FIG. 11 are views for describing a length of the curved portion (or a bent portion) of the retainer ring 130R according to another embodiment of the present disclosure.

[0069]FIG. 10 is a view for defining a curved surface when the lower curved portion 132SR has a convex shape, and FIG. 11 is a view for defining a curved surface when the lower curved portion 132SR′ has a concave shape. Referring to FIG. 10, a round value (a radius of curvature) R₁ of the lower curved portion 132SR and a cross-section length (L₁) of the lower curved portion 132SR may satisfy Relationship below.

<Relationship>

$\begin{array}{cc}{x}_1\le R_1,y_1\le R_1& 1)\end{array}$$\begin{array}{cc}\sqrt{x_1^2+y_1^2}<L_1& 2)\end{array}$

[0070]In this case, an angle θ₁ formed between an end of the lower curved portion 132SR that has a convex shape and a horizontal surface of a bottom surface thereof is greater than 0 and less than 90°. The extending direction of the end of the lower curved portion 132SR may be represented by a tangent line of a curve of the convex shape at a point approaching the bottom end of the curve, e.g., in a cross-sectional view.

[0071]Referring to FIG. 11, a round value (a radius of curvature) R₂ of the lower curved portion 132SR′ and a cross-section length (L₂) of the lower curved portion 132SR′ may satisfy Relationship below.

<Relationship>

$\begin{array}{cc}{x}_2\le R_2,y_2\le R_2& 1)\end{array}$$\begin{array}{cc}\sqrt{x_2^2+y_2^2}<L_2& 2)\end{array}$

[0072]In this case, an angle θ₂ formed between an end of the lower curved portion 132SR′ that has a concave shape and a horizontal surface of a bottom surface thereof is greater than 0 and less than 90°. The extending direction of the end of the lower curved portion 132SR′ may be represented by a tangent line of a curve of the concave shape at a point approaching the bottom end of the curve, e.g., in a cross-sectional view.

[0073]FIG. 12 is a cross-sectional view of the retainer ring 130R of FIG. 4 along the line BB′ according to another embodiment.

[0074]Referring to FIG. 12, in an embodiment, the surface 132S of the outer ring of the fluid flow path 133 may include at least one lower straight-line portion 132SL in the cross-sectional view. For example, the lower straight-line portion 132SL and the lower curved portion 132SR may be continuously disposed at the surface 132S of the outer ring starting from a region where the cleaning solution is introduced, e.g., a top end of the surface 132S.

[0075]FIGS. 13 to 17 are enlarged views of a region P2 of FIG. 12.

[0076]Referring to FIG. 13, in an embodiment, if the lower straight-line portion 132SL and the lower curved portion 132SR are continuously disposed, a thickness a3 of the lower straight-line portion 132SL in a vertical direction may be 0.3 times or less than 0.3 times a thickness a1 of the outer ring in the vertical direction. For example, the thickness a3 of the lower straight-line portion 132SL may be a thickness of the lower straight-line portion 132SL along the Z-axis direction from a start point (the highest point) to an end point (the lowest point) of the lower straight-line portion 132SL. Because the thickness a1 of the outer ring and the thickness a3 of the lower straight-line portion 132SL satisfy the above-described range, flow of the fluid in the fluid flow path 133 may be further facilitated.

[0077]In an embodiment, an angle θ₁ formed between the lower straight-line portion 132SL and a bottom surface of the outer ring 132 and an angle θ₂ formed between the lower curved portion 132SR (e.g., a line connecting two end points of the lower curved portion 132SR) and the bottom surface of the outer ring 132 may satisfy Relationship 1 below.

<Relationship 1>

$0<{\theta }_2<90°-{\theta }_1$

[0078]In the embodiment in which the straight-line portion and the curved portion are continuously disposed, the angle of the curved portion may be controlled according to the angle of the straight-line portion such that the straight-line portion and the curved portion are formed to satisfy the above-described range so that flow of the fluid may be facilitated. In FIG. 13, only the surface 132S of the outer ring including the lower curved portion 132SR and the lower straight-line portion 132SL is shown, but this is a non-limiting example, and the same or a similar shape may be equally applied to the surface 131S of the inner ring. For example, the surface 131S of the inner ring may include at least one of the upper curved portion 131SR and the upper straight-line portion 131SL, and a detailed description thereof may be referred to the descriptions of the lower curved portion 132SR and the lower straight-line portion 132SL.

[0079]Referring to FIG. 14, in an embodiment, a length in a horizontal direction of the lower straight-line portion 132SL within the fluid flow path 133 may be greater than a length in a horizontal direction of the lower curved portion 132SR within the fluid flow path 133. For example, the length r1 in the horizontal direction (X direction) of the lower straight-line portion 132SL in the surface 132S of the outer ring within the fluid flow path 133 may have a larger value than the length r2 in the horizontal direction (X direction) of the lower curved portion 132SR in the surface 132S of the outer ring within the fluid flow path 133.

[0080]Referring to FIG. 15, in another embodiment, a length in a horizontal direction of the lower straight-line portion 132SL within the fluid flow path 133 may be less than a length in a horizontal direction of the lower curved portion 132SR within the fluid flow path 133. For example, the length r1 in the horizontal direction (X direction) of the lower straight-line portion 132SL in the surface 132S of the outer ring within the fluid flow path 133 may have a smaller value than the length r2 in the horizontal direction (X direction) of the lower curved portion 132SR in the surface 132S of the outer ring within the fluid flow path 133.

[0081]Referring to FIG. 14 and FIG. 15, a design of the surface 132S of the outer ring may be changed into various forms considering the fluid flow of the chemical solution or the cleaning solution introduced into the fluid flow path 133. Additionally, the above description may be applied not only to the surface 132S of the outer ring but also to the surface 131S of the inner ring.

[0082]Referring to FIG. 16, in an embodiment, the lower curved portion 132SR′ may have a concave shape. In an embodiment, an upper curved portion 131SR′ may have a convex shape. Referring to FIG. 17, in an embodiment, the lower curved portion 132SR may have a convex shape, and the upper curved portion 131SR′ may have a convex shape. As described above, the lower curved portions 132SR and 132SR′ and the upper curved portions 131SR and 131SR′ may have the same shape or different shapes. For example, the lower curved portions 132SR and 132SR′ and the upper curved portions 131SR and 131SR′ may have a symmetrical or asymmetrical shape with respect to a line passing through a center between the lower curved portion 132SR or 132SR′ and the upper curved portion 131SR or 131SR′.

[0083]In FIG. 16 and FIG. 17, the surface 132S of the outer ring and the surface 131S of the inner ring are shown as including curved portions and straight-line portions having the same interval, but this is a non-limiting example. The curved portion and the straight-line portion may be disposed to have different intervals under a condition that facilitate flow of the fluid.

[0084]FIG. 18 is a view cross-sectional view of the retainer ring of FIG. 4 along the line B-B′ according to another embodiment.

[0085]Referring to FIG. 18, in the lower curved portion, the curved portion 132SR having a convex shape of a predetermined radius and the curved portion 132SR′ having a concave shape of a predetermined radius may be continuously disposed/formed. For example, the lower curved portion may be a member that is a curved portion having a convex shape and a concave shape, thereby having a plurality of curved shapes.

[0086]FIGS. 19 to 23 are enlarged views of a region P3 of FIG. 18.

[0087]Referring to FIG. 19, in an embodiment, in the surface 132S of the outer ring, one curved portion 132SR′ having a concave shape of a predetermined radius and one curved portion 132SR having a convex shape of a predetermined radius may be continuously disposed. For example, an upper portion of the surface 132S of the outer ring may include the curved portion 132SR′ having the concave shape of the predetermined radius, and a lower portion of the surface 132S may have the curved portion 132SR having the convex shape. For example, the surface 132S of the outer ring may have an S-shaped curved portion. The surface 132S of the outer ring may have the curved portions 132SR and 132SR′ having the concave shape and the convex shape, so that smooth movement of the fluid is facilitated by the curved portions with different slopes when the fluid is introduced. In addition, the surface 131S of the inner ring may have the same shape as that of the surface 132S of the outer ring, and a detailed description thereof may be referred to the description of the surface 132S of the outer ring. For example, the surface 131S of the inner ring and the surface 132S of the outer ring may be symmetrical.

[0088]Referring to FIG. 20, in an embodiment, a plurality of curved portions 132SR′ having a concave shape of a predetermined radius and a plurality of curved portions 132SR having a convex shape of a predetermined radius may be continuously/alternately disposed. For example, in the surface 132S of the outer ring, a plurality of units, each including a curved portion 132SR′ having the concave shape and a curved portion 132SR having the convex shape may be continuously/repeatedly disposed.

[0089]Referring to FIG. 21, in an embodiment, the surface 132S of the outer ring may include at least one lower straight-line portion 132SL. For example, the lower straight-line portion 132SL may be disposed between a plurality of curved portions 132SR′ having concave shapes and a plurality of curved portions 132SR having convex shapes. Referring to FIG. 22, in an embodiment, the lower straight-line portion 132SL may be disposed prior to (e.g., above) a plurality of curved portions 132SR′ each having a concave shape and a plurality of curved portions 132SR each having a convex shape. In another embodiment, the lower straight-line portion 132SL may be disposed following (e.g., below) the plurality of curved portions 132SR′ having the concave shape and the plurality of curved portions 132SR having the convex shape. The sequences of the shapes on the surfaces of the fluid flow path 133 described in this disclosure may be based on the direction/sequence of flow of the fluid though the fluid flow path 133.

[0090]The surface 132S of the outer ring may more easily control flow of the fluid by disposing the straight-line portion and the curved portion in various shapes.

[0091]Referring to FIG. 23, in an embodiment, a cross-sectional length of the curved portion 132SR′ having a concave shape and the curved portion 132SR having a convex shape that are a preceding portion (e.g., an upper portion) may be different from a cross-sectional length of the curved portion 132SR′ having a concave shape and the curved portion 132SR having a convex shape that are a following portion (e.g., a lower portion). For example, the cross-sectional length of the curved portion 132SR′ having the concave shape and the curved portion 132SR having the convex shape that are the preceding portion (e.g., the upper portion) may be formed shorter than the cross-sectional length of the curved portion 132SR′ having the concave shape and the curved portion 132SR having the convex shape that are the following portion (e.g., the lower portion), so that flow of the fluid may be easily controlled when the fluid is introduced into the fluid flow path 133. Cross-sectional lengths of the present disclosure may be lengths in cross-sectional views.

[0092]Although FIGS. 19 to 23 are described based on the surface 132S of the outer ring, this may also be applied to the surface 131S of the inner ring so that a description of the surface 131S of the inner ring may be referred to the descriptions of FIGS. 19 to 23.

[0093]FIG. 24 is a view for describing a length of the curved portion of the retainer ring 130R according to another embodiment of the present disclosure.

[0094]Referring to FIG. 24, when each of the surface 131S of the inner ring 131 and the surface 132S of the outer ring 132 includes a plurality of convex curved portions and/or a plurality of concave curved portions, an R value (a radius of curvature) and a cross-sectional length of each curved surface may be checked/determined. For example, the R value (the radius of curvature) of the convex curved surface may be set by a relationship (α<R), and an angle θ₁ formed between the bottom end portion of the convex curved surface and a horizontal line and the length X of the curved surface in the cross-sectional view are expressed in Relationship below.

<Relationship>

$\begin{array}{cc}\alpha \sqrt{2}<X<\frac{\mathrm{\pi \alpha }}{2}& 1)\end{array}$$\begin{array}{cc}45°<{\theta }_1<90°& 2)\end{array}$

[0095]The R value (the radius of curvature) of the concave curved surface may be set by a relationship (β<R), and an angle θ₂ formed between the bottom end portion of the concave curved surface and a horizontal line and the length Y of the curved surface in the cross-sectional view are expressed in Relationship below.

<Relationship>

$\begin{array}{cc}\beta \sqrt{2}<Y<\frac{\mathrm{\pi \beta }}{2}& 1)\end{array}$$\begin{array}{cc}0°<{\theta }_2<45°& 2)\end{array}$

[0096]By forming the fluid flow path 133 between the inner ring 131 and the outer ring 132 in a plurality of curved surfaces, an optimized structure for the fluid flow may be implemented.

[0097]Even though different figures illustrate variations of exemplary embodiments and different embodiments disclose different features from each other, these figures and embodiments are not necessarily intended to be mutually exclusive from each other. Rather, features depicted in different figures and/or described above in different embodiments can be combined with other features from other figures/embodiments to result in additional variations of embodiments, when taking the figures and related descriptions of embodiments as a whole into consideration. For example, components and/or features of different embodiments described above can be combined with components and/or features of other embodiments interchangeably or additionally to form additional embodiments unless the context clearly indicates otherwise, and the present disclosure includes the additional embodiments

[0098]The present disclosure is not limited to the embodiments, but may be manufactured in a variety of different forms, and those of ordinary skill in the art to which the present disclosure pertains will understand that the present disclosure may be implemented in other specific forms without changing the technical spirit or an essential feature of the present disclosure. Therefore, it should be understood that the above-described embodiments are just examples in all aspects and are not limited thereto.

DESCRIPTION OF SYMBOLS